In general, command/address signal may be applied to a semiconductor device such as a semiconductor memory device from a controller and it need to meet a setup/hold time specification. With the increase of the operating speed of the controller, various methods for the command/address signal to meet the setup/hold time specification are being researched.
By checking a delay amount of the command/address signals occurring while the controller applies the command addresses to the semiconductor device, the controller performs an operation of controlling the setup/hold times of the command/address signals (hereinafter, referred to as a ‘calibration operation’). The semiconductor device latches the command/address signals and outputs the latched command/address signals through data pads, and the controller is fed back with the command addresses which are outputted through the data pads.
However, in the case where the number of the command/address signals is greater than the number of the data pads, the semiconductor device cannot output the command/address signals to the data pads. Accordingly, since the controller cannot be fed back with the command/address signals, the setup/hold times of the command addresses cannot be controlled.